The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems are used to treat substrates such as semiconductor wafers. Examples include wet or dry treatments for drying, etching, cleaning, polishing and/or material deposition. In some applications, a spin chuck uses a liquid dispenser including one or more liquid nozzles to dispense a treatment liquid onto a substrate as the substrate is rotated. As feature sizes decrease and aspect ratios increase, pattern collapse may occur when performing wet treatment such drying of the substrates.
Referring now to FIGS. 1A-1C, a substrate 2 includes features 1. In some examples, the features 1 include high aspect ratio (HAR) features such as fins. During processing, the substrate 2 is rinsed with one or more liquids to remove processing liquids, reactants and/or particles. For example, the substrate 2 can be rinsed with deionized (DI) water and isopropyl alcohol (IPA), as shown at 3 in FIG. 1A surrounding the features 1.
As the substrate 2 is dried, the IPA 3 evaporates. However, surface tension and the high aspect ratio of the features 1 causes the IPA 3 to be removed more slowly from spaces between the features 1. A meniscus may be formed as shown at M in FIG. 1B. As drying of the substrate 2 continues, the surface tension of the IPA 3 pulls the features 1 toward each other as shown in FIG. 1C, which causes leaning of the fins and defects.
Some processes attempt to reduce pattern collapse by using a rinse liquid such as IPA that has a lower surface tension than DI water. Additionally the rinsing can be performed at an elevated temperature. These approaches have had a limited effect on reducing pattern collapse.